Supermarkets have distinguished requirements, and these requirements can only be met by sufficiently controlling space humidity levels. Moisture control is the greatest concern for a supermarket; too much moisture negatively affects the refrigeration system, and too little moisture negatively affects the fresh fruit and vegetables. For this reason, there is a need to target optimum dehumidification for the supermarket without jeopardizing the comfort and efficiency of the store.
U.S. Pat. No. 6,508,066 describes a single coil dual path dehumidification. The system draws in outside air which is circulated along its own path. A cooling coil is disposed in the dedicated outside path. The outside air therefore passes over the cooling coil and is dehumidified prior to being mixed with any other air. The system also draws in return air from the interior of building. The return air is then drawn into the housing where it is mixed with the outside air. Only the outside air passes over the cooling coil. The dehumidified outside air and the cooled return air form a supply air stream that is delivered to the interior of the building.
U.S. Pat. No. 6,792,767 to Pargeter, et al. describes a control system for a heating, ventilation, and air conditioning (HVAC) unit for controlling the humidity and temperature of interior building space at desired levels regardless of the outside temperature and humidity conditions. The control system employs a combination of modulated return air bypass, modulated capacity compressor, and modulating hot gas reheat. Pargeter does not describe a way of independently controlling the airflow across the cooling coil and the airflow bypassing the cooling coil for fine temperature and humidity adjustments.
Accordingly, there is still a need to provide an air conditioning system capable of fine control over humidity and temperature levels, particularly for use in supermarkets having fine humidity and temperature requirements.